1. Field of the Invention
This invention relates to pumping apparatus for transporting fluids from a well formation to the earth's surface. More particularly, embodiments of the invention pertain to a rod pump which can be pulled in a collapsed position.
2. Description of the Related Art
Many hydrocarbon wells are unable to produce at commercially viable levels without assistance in lifting formation fluids to the earth's surface. In some instances, high fluid viscosity inhibits fluid flow to the surface. More commonly, formation pressure is inadequate to drive fluids upward in the wellbore. In the case of deeper wells, extraordinary hydrostatic head acts downwardly against the formation, thereby inhibiting the unassisted flow of production fluid to the surface.
A common approach for urging production fluids to the surface includes the use of a mechanically actuated, positive displacement pump. Mechanically actuated pumps are sometimes referred to as “sucker rod” pumps because of the reciprocal movement of the pump necessary for positive displacement is induced through reciprocal movement of a string of sucker rods above the pump from the surface.
A sucker rod pumping installation consists of a positive displacement pump disposed within the lower portion of the production tubing. The installation includes a piston which is moved in linear translation within the tubing by means of steel or fiberglass sucker rods. Linear movement of the sucker rods is typically imparted from the surface by a rocker-type structure. The rocker-type structure serves to alternately raise and lower the sucker rods, thereby imparting reciprocating movement to the piston within the pump downhole.
When a rod pump is in need of repair or replacement, a lubricator and a rig may be required to pull the rod pump from the production tubing. Typically, a rod pump is pulled in an extended position (i.e., the pump is in an upstroke position and at maximum length) which may require equipment other than commonly available lubricator lengths and rigs. Thus, delays in repairs and service may result because of the unavailability of necessary equipment. These delays results in costly down time and loss of production. Also, long lubricators become a safety concern because it is difficult to support long (tall) lubricators.
Therefore, there is a need for a rod pump which can be pulled in a collapsed position which reduces or minimizes the length of the rod pump and reduces the length of the lubricator required to remove the rod pump from the production tubing.